We've had this problem with Dell servers, the seagate Archive Python (DDS3 - 12Gb Native, 24Gb Compressed [optimal])The fix that solves 90% of these types of issues is a firmware upgrade for the tape drive. It needs to be firmware revision 743b. This is not on Dells web site for download, but can be obtained by calling them on 0870 9080500 - Dell Tech Support. You will need to quote the Tag number and model of the server (its on the back (usually a little white label).